1. Field of the Invention
This invention relates generally to oil film bearings of the type employed to rotatably support the tapered necks of rolls in a rolling mill, and is concerned in particular with an improvement in the sleeves employed in such bearings, as well as in the manner of rotatably fixing such sleeves on and axially removing such sleeves from the roll necks.
2. Description of the Prior Art
In a conventional oil film bearing of the type shown in FIG. 7, a sleeve 10 is axially received on the tapered section 12 of a roll neck protruding axially from the roll body 16. The sleeve has a tapered interior surface 18 axially received on the tapered roll neck section 12, and a cylindrical outer surface 20 journalled for rotation in a bushing 22 contained in and fixed relative to a chock 24. One end of the sleeve is provided with a radially outwardly protruding circular flange 26, as well as with a radially inwardly protruding circular collar 28. Keyways 30 are machined into the collar 28. Keys 32 are received in notches 34 in a reduced diameter cylindrical extension 36 of the roll neck. The keys 32 protrude into the keyways 30 in the inner sleeve collar 28 to fix the sleeve 10 against rotation relative to the tapered roll neck section 12.
Other conventional bearing components include an inboard seal assembly 38, sleeve retaining ring 40, roller thrust bearing 42 and associated retaining and outboard sealing elements generally depicted at 44.
The chock 24, bushing 22, sleeve 10 and the other above described conventional components are axially receivable on and removable from the roll neck as a single unit or assembly. During axial removal, the chock 24 is pulled in the direction of arrow 46. The bushing 22 follows the chock, and by virtue of the interengagement of the outboard end of the bushing with the sleeve flange 26, the sleeve is axially dislodged and removed from the tapered section 12 of the roll neck.
With reference to FIG. 8, it will be understood that the sleeve 10 is machined from a cylindrical forging 48 initially produced with external and internal diameters indicated respectively at "X" and "Y". FIG. 9 shows the longitudinal sectional profile of the sleeve 10 superimposed on a broken line outline of the longitudinal sectional profile of the forging 48. It will be seen that outer diameter X of the forging is dictated by the necessity to accommodate the circular external flange 26, and that the inner diameter Y is likewise dictated by the necessity to accommodate the circular internal sleeve collar 28. During machining of the forging to produce the sleeve, metal is removed externally at "a" and "b", and internally at "c" and "d". The resulting loss of metal through machining amounts to approximately 2.6 times the weight of the finished sleeve. Thus, a 4,300 kg forging is required to produce a sleeve weighing approximately 1,635 kg, with approximately 2,665 kgs of metal being lost during the machining process. The cost of this lost metal is substantial, as is the cost of repeatedly heat treating it during forging and subsequently removing it during the machining process.
The objective of the present invention is to achieve significant reductions in these costs by reducing both the size of the forging required to produce the sleeve and the amount of metal lost during subsequent machining of the forging.